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germ-layer
Значение термина germ-layer в knolik
germ-layer - germ-layer
germ-layer - (Zool.). One of the main layers or groups of cells which can be distinguished in an embryo during and immediately after gastrulation. These layers are roughly similar in arrangement, and in ultimate differentiation, in most animals. There are two in diploblastic animals, endoderm and ectoderm. In triploblastic animals there is in addition the meso-derm. There is general agreement as to which layer gives rise to which tissues, e.g. nervous tissue is characteristically ecto-dermal, cartilage both mesodermal and ectodermal. (But it is not agreed to which germ-layer the chordate notochord belongs.) It is now known that the equating of the layers in different groups cannot be pushed to extremes, as it formerly was, by supposing that a given sort of tissue is in all groups of animals entirely derived from a given germ-layer. Though the general architecture is similar there are also numerous differences between groups.
Рядом со словом germ-layer в knolik
| germinal vesicle | В начало буква "" буквосочетание "" | germ-plasm |
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